Income Taxes - Reconciliation of Total Amounts of Unrecognized Tax Benefits (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Unrecognized tax benefits, balance at the beginning	$ 2,459	$ 2,139	$ 3,495
Additions based on tax positions related to the current year	10	371	351
Additions for tax positions of prior years		317
Reductions for tax positions of prior years	(676)		(135)
Lapse of statute of limitations	(735)	(670)	(1,318)
Additions (reductions) of interest and penalties	(712)	334	(108)
Translation adjustments	137	(32)	(146)
Unrecognized tax benefits, balance at the ending	$ 483	$ 2,459	$ 2,139